To establish an easier and more accurate method to determine silicon content in rice, several main parameters of silicon molybdenum-blue spectrophotometry were optimized in combination with 2 sample pretreatments, digestion and autoclaving. By using ascorbic acid as a reductant, with the color development time of the silicon molybdenum yellow and the stable time of silicon molybdenum blue for 5 and 25 min, respectively, optimal silicon content in rice was achieved at 600 nm wavelength by molybdenum-blue spectrophotometry. For sample pretreatment, the digestion method was more effective for silicon extraction than autoclaving. Briefly, the optimized method facilitates the determination of silicon content in rice and other plants and could lay a theoretical foundation for further research of the mechanism of silicon absorbance and transportation.